TurnItIn has helpful general advice on this issue (from the post “Plagiarism or Similarity” at the TurnItIn Blog):
“There is a very distinct difference between what Turnitin flags as matching text (aka: similarity index) and plagiarism. Turnitin will highlight ANY matching material in a paper—even if it is properly quoted and cited. Just because it appears as unoriginal does not mean it is plagiarized; it just means that the material matches something in the Turnitin databases.
We leave it to the instructors to look at a paper and the originality report to make the determination of whether or not something is plagiarism, and to what extent—intentional plagiarism, unintentional plagiarism, improper/lack of citation, or mere coincidence. Best practices from instructors suggest that Turnitin OriginalityCheck be used as a teaching tool to address citation and academic honesty, not only as a punitive tool.”
TurnItIn also offers a useful and more detailed pages on its website: The Similarity Report
Article ID: 264
Created On: Fri, Nov 18, 2016 at 3:12 PM
Last Updated On: Wed, Feb 27, 2019 at 10:40 AM
Authored by: Amy Sorensen [Amy.Sorensen@cccs.edu]
Online URL: https://kb.ccconline.org/article.php?id=264